The invention disclosed herein relates to a laser level assembly. The laser level assembly is an apparatus that provides a laser beam which can be used for applications including but not limited to surveying and construction levelling and marking out.
The use of a rotating laser beam to define a plane is well known. These devices have typically incorporated a semiconductor laser fixed within a housing projecting its laser light beam into a spinning prism which effects translation of a typically vertically projected beam into a rotating horizontal beam. Attachments have been available which in like manner effect a rotating vertical laser beam, however these require the dismantling of a set up device to permit fitting. Therefore the device must be relocated and reset when changing from a horizontal rotating laser beam to a vertical rotating laser beam.
In such arrangements the laser beam is projected along the axis about which a platform supporting a prism rotates. An electric motor is used to drive the platform typically through a belt or gear cog arrangement. Thus, the known devices rotate fully about an axis defining a full plane. This means that there can be a significant delay at a remote sensing location for the beam to rotate between each transversing of the location. The speed of rotation may be variable but this can lead to a further problem. The effective angular velocity can be very high with the effect that the laser radiation flux experienced by a sensor may be too low to be reliably sensed. Thus increasing the speed of rotation can lead to unreliable sensing of the laser beam so requiring a slower speed of rotation, and slowing the speed of rotation increases the time between each transversing by the beam of the sensor. Electronic design of the sensor may accommodate some of these problems.
Further problems are exhibited by the known systems. The use of quality optical elements such as a prism leads to an expensive device. Further, the mechanical supporting structure also typically needs to be to a very high tolerance with the result again that the device is expensive.
To overcome some of these problems a number of devices have been proposed.
U.S. Pat. No. 5,287,365 to Nielsen et al describes a laser apparatus where a semiconductor laser is mounted onto a platform which is rotated by an electric motor. The platform has a central shaft which is driven by an electric motor through a belt drive. Electrical power is transferred to the shaft and thus to the laser through slip rings. Control of the electrical motor is limited to on/off and speed control.
As disclosed the apparatus provides essentially a horizontal plane in which the laser beam rotates.
In U.S. Pat. No. 4,973,158 to Marsh an instrument is disclosed which is intended to be fitted to a surveyor""s transit and telescope. It is disclosed as rotating in a vertical plane aligned with the plane of view of a telescope. There is no disclosure of being able to change the plane of laser beam rotation in a convenient and simple manner. Rather the instrument is limited to improvements related to a transit level rather than a more general instrument.
The disclosed device utilises a rotatable shaft which has a platform at each end. A semiconductor laser is mounted on one platform with drive and control circuitry mounted on the other platform. To power the laser, electrical power is supplied to the platforms through electrical brushes to the shaft. The shaft and the platforms are rotated by an electric motor through gear cogs.
In U.S. Pat. No. 5,400,514 to Imbrie et al an apparatus is disclosed where a laser pointer is centrally supported on a shaft. The shaft is belt driven to rotate by an electric motor within a rectilinear body. The electrical and electronic circuitry for the electric motor and the laser pointer are completely separate. The laser pointer includes drive circuitry and battery for electrical power supply independent of the rest of the apparatus. Accordingly, the electrical motor must rotate the semiconductor laser and the necessary circuitry.
The body of the apparatus disclosed does include means to set up the apparatus so that the plane within which the laser radiation projects is either vertical or horizontal. For this purpose three orthogonally mounted spirit bubble levels are provided with two sets of adjustable feet projecting from adjacent sides. To change the plane within which the laser beam rotates the apparatus must be set up afresh.
It is a proposed object of this invention to provide an apparatus to obviate or minimise at least one of the aforementioned problems, or at least provide the public with a useful choice
The invention may be said to reside, not necessarily in the broadest or only form, in laser level apparatus including body means, platform means supported by the body means and selectively pivotable about a first axis, drive means supported by the platform means and selectively pivotable about a second axis transverse to the first axis, head means rotatably supported by the drive means and adapted to be selectively rotated by the drive means about a third axis transverse to the second axis, laser means supported by the head means to selectively project laser radiation from the head means transverse the third axis, laser means includes a semiconductor laser adapted to produce the laser radiation, and the apparatus includes a first rotatable electrical connection means and a second rotatable electrical connection means through which electrical power is supplied to the semiconductor laser.
In another preferred form, the drive means includes a motor with a rotatable shaft driven thereby which is coaxial with the second axis and the head means is supported by the shaft.
In one preferred form, wherein the shaft has two partly coaxial electrically conductive parts insulated one from the other, and the first rotatable electrical connection means and the second rotatable electrical connection means each includes a respective one of the parts. According to a preferred form, the first rotatable electrical connection means and the second electrical connection means respectively includes electrical brush arrangements. It will be appreciated that other arrangements known to the art similar in effect to the electrical brush arrangement can be used as desired.
The separation of the laser means and the electrical power source means the weight of the laser means can be reduced so easing the load experienced by the drive means during rotating the laser head. In one preferred form, the laser means may be rotated and varying and relatively high speeds and dithered within an arc. For such action it is desirable for the rotating laser means to have a relatively low inertia.
It will be appreciated that the ability to rotate the various parts of the apparatus with respect to other parts permits flexibility and ease of use.
In a preferred form, the laser radiation projected by the laser means is substantially perpendicular to the third axis, the third axis is substantially perpendicular to the second axis, the second axis is substantially perpendicular to the first axis, and the drive means may be selectively rotated to a first configuration where the third axis is substantially parallel or coaxial with the first axis and to a second configuration where the third axis is substantially perpendicular to the first axis.
In a further preferred form, the body means has levelling means to enable adjustment of the support of the platform means such that the first axis is within a vertical plane, and thereby when the apparatus is in the first configuration the laser radiation projected by the laser means is substantially within a horizontal plane and when the apparatus is in the second configuration the laser radiation projected by the laser means is substantially within a vertical plane. By levelling the body means so that the first axis is vertical the laser beam can be rotated in a horizontal or vertical plane. In the case of a vertical plane the platform means can be rotated about the first axis so permitting the vertical plane and a subsequent vertical plane to be at a known horizontal angle one with respect to the other. This can be used, for example, to set out two adjacent sides of a building.
According to one preferred form, the drive means may be selectively rotated and secured in a configuration between the first and second configurations. This permits the plane within which the laser beam rotates to be a sloping plane. This can be used, for example, to indicate a slope for earth moving machinery to work to as may be required for drainage control of a land site.
According to a preferred form, the apparatus is one including levelling means acting between the body means and the platform means. In a preferred form, the levelling means includes two spirit bubbles set transverse to each other and within or upon the platform means for indication of levelness of the platform means, and foot screws spaced about the platform means and acting against the body means with which to adjust the relative position of the platform means with respect to the body means and thereby with the spirit bubbles permit the levelling of the platform means. In an alternative preferred form, the levelling means includes two spirit bubbles set transverse to each other and within or upon the platform means for indication of levelness of the platform means, and the platform means includes a shaft projecting substantially perpendicular to a platform plate and substantially parallel to the first axis into the body means through a first hole and at substantially a distal end of the shaft, two spring means act to bias the shaft against the action of two radially spaced transverse acting screws with which the platform means may be levelled by tilting the shaft relative to the body means. In a further preferred alternative form, the levelling means includes semi-automated or automated means to effect levelling of the platform means.
In another preferred form, the apparatus is one including a stand for supporting the body means in an elevated position above a floor or ground surface. In a preferred form the body means is adapted to rest upon an suitable relatively flat surface. For example a table top or other surface which is reasonably flat and level to support the apparatus and permit levelling of the platform means relative to the body means.
In a preferred form, either the platform means includes a graduated circular scale and the body means includes an indicator mark or vice versa, therewith the rotation of the platform means about the first axis can be determined. By use of the scale an indication of rotation of the platform means with respect to the body means can be provided. In a preferred form, the graduated circular scale is selectively rotatable and securable thereby permitting the scale to be set to the indicator mark and the platform means rotated a desired quantity of rotation indicated by the scale. In this manner a vertical plane of laser beam rotation may be set a specific angle relative to a previous vertical plane of laser beam rotation. In a preferred form, the platform means or the body means as the case may be includes a ring upon which the indicator mark is, and the ring is selectively rotatable and securable thereby permitting the indicator mark to be rotated to a point closest to the graduated circular scale. Should the body means and the platform means be angled one to the other then the plane of the graduated scale and the ring will also be angled. Accordingly there will be a side where the ring and scale are closest and a side opposite where they are furthest. Thus to improve accuracy and ease of operation it is desirable to adjust the indicator mark to be as near as possible to the scale.
According to a preferred form, either the platform means includes a graduated scale and the drive means includes an inclination mark or vice versa, therewith the rotation of the drive means about the second axis can be determined and set thereto.
In another preferred form, the drive means includes an electric motor and control means to control the rotational position thereof. In a preferred form, the drive means includes an electric stepper motor and control means to control the rotational position thereof and the active state of the laser means. In preference, the control means is contained within the platform means and connected to the stepper motor and laser means via electrical wiring. Preferably, the control means permits control of the stepper motor such that it may be rotated to a desired rotational position, continually rotating about the third axis, or oscillating between two rotational positions. It will be appreciated that other forms of motors may be used as desired.
In a preferred form, the laser head includes means to collimate the laser with respect to the third axis. This permits adjustment so that the third axis is perpendicular to the plane within which the laser emits a rotating beam of radiation. In a preferred form, the laser head includes support means for supporting the laser within the laser head, the support means including a resilient first bearing means adapted to provide a firm hold of the laser, and a second bearing means including a resilient bearing surface against which and along a collimator axis substantially parallel to the third axis an adjustable means presses the laser. In this manner, the first bearing permits slight rotation of the laser in response to adjustment of the adjustable means which can be used to collimate the laser with respect to the third axis. A locking means to secure the laser in place after collimation can be incorporated as desired.
According to a preferred form, the apparatus is one including a remote control unit adapted to transmit control setting signals to a receiver within the control means thereby to effect control of the stepper motor and the laser means.
In a preferred form, there is provided an apparatus, substantially as herein described, and a detector staff with an array of detectors each for detection of the laser radiation. In preference, the array of detectors includes two sets of the detectors each set being aligned alone intersecting first and a second line such that the detectors form a cross. Other intersecting forms can be used as desired. In a preferred form, the laser radiation is emitted in a plane and the detector array is moved so that it is aligned with either the first or the second line and the control means is commanded to effect reduced dithering of the laser radiation within the plane until the laser radiation is emitted in a single direction, whereafter the detector array can be centered with respect to the laser radiation.
Without limiting the invention disclosed herein, one known system including a laser level instrument and a remote control is disclosed in PCT Patent Application WO 96/01978.
In one preferred form, the platform means and body means have aperture means such that the first axis is unobstructed and that the laser means may project laser radiation through the platform means and body means. Further, according to one form the drive means is supported by the platform means so as to be rotatable through 180xc2x0 relative to the platform means. By this means the laser may be orientated to shine through the platform and body means and may be used as a plumb line. Also setting the apparatus above a style, levelling the apparatus and by then using the plumb line feature the apparatus may be accurately located relative to the style. Once so set up rotation of the platform means with respect to the body means does not change the first axis being within the plane of the laser radiation. This may facilitate marking out of lines such as for walls and fences.